1. Field of the Invention
The invention relates to means for smoothening (burnishing) surfaces of disks for disk memories and somewhat more particularly to a device and method for smoothening operational surfaces of magnetic disks for magnetic disk memories, as are used in data processing systems.
2. Prior Art
In order to scan memory disks in magnetic disk memories for data processing systems with magnetic heads having altitude levels of less than 1 .mu.m, a very low degree of roughness on the disk surface, far below 1 .mu.m, is required. Such degree of roughness is significantly below that presently attainable in the manufacture of such disks. The surface error or irregularities in the form of projecting peaks and the like typically present after disk manufacture, must be eliminated by a subsequent work-step, during which the projecting peaks and the like are eroded or levelled.
It is known to level or burnish the planar surfaces of such disks by means of special "burnishing heads" which scan the operative disk surface at reduced speeds and at altitude levels which are far below normal operating speeds and altitude levels of magnetic heads. Due to the reduced speed and low altitude level utilized during such burnishing or smoothening process, a contact occurs at uneven surface areas between the burnishing head and the disk surface being scanned. This contact causes the roughness areas to be either eroded or levelled.
With the foregoing arrangement, the burnishing head may be equipped with a piezo-electric element which generates an impulse-like signal upon contact between the burnishing head and the disk surface. The disk is considered to be smoothened (burnished) when such signals attain a minimum value or are no longer generated.
A disadvantage of the foregoing procedure for smoothening the surfaces of disk memories is that the burnishing heads still fly too high and thus fail to achieve an optimum smoothening. If one were to further reduce the disk speed so as to further reduce the altitude level of the burnishing heads, insufficient energy for the desired smoothening would result.